Table 23. NAVconfig heading lock options
Normal This option assumes the heading of the vehicle does not change by more than 2° while
the vehicle is stationary. The heading accuracy recovers quickly when the vehicle
moves.
Very tight The option assumes the heading of the vehicle does not change by more than 0.3°
while the vehicle is stationary. The recovery is fast if the heading of the vehicle does
not change but will be slow if the vehicle turns before it moves. This option can
cause problems during the warm-up period if the vehicle remains stationary for a
long time and then drives suddenly.
Note: The heading of most vehicles does change if the steering wheel is turned while the vehicle is
stationary. Junctions and pulling out of parking spaces are common places where drivers turn the
steering wheel while not moving.
Garage mode
The Garage mode option is used to stabilise the RT’s outputs when GNSS is not available.
For example, GNSS can be blocked when the vehicle returns to the garage to have some
modifications. Without Garage mode enabled, the RT may drift too far and may not be able
to recover.
When Garage mode is active, the RT applies a gentle velocity update and assumes that the
vehicle is stationary. This keeps the roll, pitch and velocity within acceptable limits while
the RT has no GNSS. With heading lock also enabled, the RT can also keep the heading
accurate while stationary.
When using this option, try to keep the vehicle’s movement inside the garage to a
minimum and exit the garage through the same door the car entered.
Surface tilt
The surface tilt settings are used to compute the roll, pitch (and heading) compared to a
flat inclined surface. The roll and pitch from the RT products are measured compared to
gravity. Most test tracks are built at an angle so rain water runs off and the track dries
faster. As the vehicle drives up the incline, the pitch shows a positive value; as the vehicle
drives down the incline the pitch shows a negative value; the value changes with a
sinusoidal pattern as you drive round a circle. The roll angle shows a similar effect.
Using the surface tilt option, the roll and pitch compared to the inclined surface can be
output as well. The NAVdisplay software contains a tool for working out the surface
angles. NAVconfig can be used to configure the surface’s angle if it has been measured
already. These settings can be input in the Environment section within NAVconfig.
Figure 32 shows the Surface tilt properties settings.
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